| Message ID | YuV9apZGNmGfjcor@p100 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vt: Clear selection before changing the font | expand |
On 7/31/22 00:50, Helge Deller wrote: > When changing the console font with ioctl(KDFONTOP) the new font size > can be bigger than the previous font. A previous selection may thus now > be outside of the new screen size and thus trigger out-of-bounds > accesses to graphics memory if the selection is removed in > vc_do_resize(). > > Prevent such out-of-memory accesses by dropping the selection before the > various con_font_set() console handlers are called. > > Signed-off-by: Helge Deller <deller@gmx.de> Tested-by: Khalid Masum <khalid.masum.92@gmail.com> > Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com > > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > index dfc1f4b445f3..3f09205185a4 100644 > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -4662,9 +4662,11 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op) > console_lock(); > if (vc->vc_mode != KD_TEXT) > rc = -EINVAL; > - else if (vc->vc_sw->con_font_set) > + else if (vc->vc_sw->con_font_set) { > + if (vc_is_sel(vc)) > + clear_selection(); > rc = vc->vc_sw->con_font_set(vc, &font, op->flags); > - else > + } else > rc = -ENOSYS; > console_unlock(); > kfree(font.data); > @@ -4691,9 +4693,11 @@ static int con_font_default(struct vc_data *vc, struct console_font_op *op) > console_unlock(); > return -EINVAL; > } > - if (vc->vc_sw->con_font_default) > + if (vc->vc_sw->con_font_default) { > + if (vc_is_sel(vc)) > + clear_selection(); > rc = vc->vc_sw->con_font_default(vc, &font, s); > - else > + } else > rc = -ENOSYS; > console_unlock(); > if (!rc) {
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index dfc1f4b445f3..3f09205185a4 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -4662,9 +4662,11 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op) console_lock(); if (vc->vc_mode != KD_TEXT) rc = -EINVAL; - else if (vc->vc_sw->con_font_set) + else if (vc->vc_sw->con_font_set) { + if (vc_is_sel(vc)) + clear_selection(); rc = vc->vc_sw->con_font_set(vc, &font, op->flags); - else + } else rc = -ENOSYS; console_unlock(); kfree(font.data); @@ -4691,9 +4693,11 @@ static int con_font_default(struct vc_data *vc, struct console_font_op *op) console_unlock(); return -EINVAL; } - if (vc->vc_sw->con_font_default) + if (vc->vc_sw->con_font_default) { + if (vc_is_sel(vc)) + clear_selection(); rc = vc->vc_sw->con_font_default(vc, &font, s); - else + } else rc = -ENOSYS; console_unlock(); if (!rc) {
When changing the console font with ioctl(KDFONTOP) the new font size can be bigger than the previous font. A previous selection may thus now be outside of the new screen size and thus trigger out-of-bounds accesses to graphics memory if the selection is removed in vc_do_resize(). Prevent such out-of-memory accesses by dropping the selection before the various con_font_set() console handlers are called. Signed-off-by: Helge Deller <deller@gmx.de> Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com